1. Field of the Invention
The invention relates to an analog-to-digital conversion device and stages thereof, and more particularly to a time-interleaved analog-to-digital conversion device and stages thereof.
2. Description of the Related Art
Driven by digital applications development, digital applications have become more and more popular, such as blue-ray discs. Signals transmitted to digital applications have to be digitized by a digital signal processing procedure. Thus, for communication between analog applications and digital applications, analog-to-digital conversion (ADC) devices are used to digitize input signals. Since digital signals are analyzed and processed more easily than analog signals, the ADC devices become more important for integrated circuits. For example, a PRML (Partial Response Maximum Likelihood) read channel for a blue-ray disc requires an 8-bit ADC device with minimal latency. Therefore, a high speed ADC device is a key component to improve speed of electronic devices, such as a blue-ray disc drive.
FIG. 1A shows a conventional pipeline ADC device. Referring to FIG. 1, a pipeline ADC device 1 comprises a sample-and-hold unit 11, a plurality of ADC stages 101-10N, and an error correction unit 12. The sample-and-hold unit 11 samples a received data D10 to generate an analog input data VIN1. Except for the last stage 10N, each ADC stage 10i receives a respective analog input data VINi and outputs a corresponding analog output VOUTi to serve as an analog input data VINi+1 of the next ADC stage, wherein 1□i<N. Each ADC stage also generates a digital data DOUTi to the error correction unit 12. Referring to FIG. 1B, each ADC stage comprises an ADC unit 100, a digital-to-analog conversion (DAC) unit 101, a subtracter 102, and an amplifier 103. Generally, the ADC unit 100 is a flash-type unit. Referring to FIG. 2, the flash-type ADC unit 100 comprises a sample-and-hold unit 20, a pre-amp unit 21, and a latch unit 22. However, kick-back noise easily occurs in the sample-and-hold unit 20. Moreover, if the pipeline ADC device 1 is desired in a time-interleaved structure, two sets of the sample-and-hold unit 20, the pre-amp unit 21, and the latch unit 22 are required for each ADC stage, resulting in larger area and higher power consumption requirements.
Thus, it is desired to provide an ADC device with a time-interleaved structure without the above drawbacks.